1. Field of the Invention
The invention relates to corrosion-inhibited aqueous solutions and particularly relates to corrosion-inhibited antifreeze compositions containing dicyclopentadiene dicarboxylic acid salts useful as coolants such as in the cooling system of an internal combustion engine.
2. Other Inhibitors Known in the Art
It is well known to use dicarboxylic acids as corrosion inhibitors in aqueous systems. For example, Jones in U.S. Pat. No. 2,726,215 teaches that dicarboxylic acids; namely sebacic acid and azelaic acid, and their alkali and alkali metal salts are useful corrosion inhibitors in aqueous solutions. The use of a mixture of sodium sebacate (sodium salt of sebacic acid) and benzotriazole was disclosed as a useful corrosion inhibitor in engine coolants by G. Butler, et al. in "Inhibitor Formulations for Engine Coolants," British Corrosion Journal, Vol. 12, No. 3, 1977, pp 171-174.
U.S. Pat. No. 3,931,029 to Dutton, et al. teaches the use of certain unsaturated cycloalkylene dicarboxylic acids as antifreeze additives to inhibit corrosion of contacted solder alloys. Corrosion inhibitors containing an imidazoline derivative, a carboxylic acid or its metal salt and/or a phosphate are used for steel in brackish or acidic water according to Chemical Abstracts, Vol. 99, paragraph 126713x, 1983, which describes Japanese Kokai 58-84,981. U.S. Pat. No. 4,382,008 reveals a corrosion-inhibited antifreeze containing a triazole, an alkali metal borate, an alkali metal benzoate, an alkali metal silicate and an alkali metal salt of a C.sub.7 to C.sub.13 dibasic organic acid. The use of sodium sebacate as a corrosion inhibitor in phosphate-based antifreezes is further seen in the Derwent Abstract of Week E14 for French Certificate of Utility 2,489,355 to Perrot.
The Derwent Abstract of Week K18 for European Pat. No. 77,767-B teaches the use of water-soluble salts of dicarboxylic acids having at least three carbon atoms as antifreeze corrosion inhibitors. These acids are malonic, succinic, glutaric and adipic acids along with smaller proportions of C.sub.8 and/or C.sub.10 dicarboxylic acids. A mixture of a siloxane-silicate copolymer with an azole was found effective in reducing the corrosion of high-lead solder and aluminum in aqueous liquids according to U.S. Pat. Nos. 4,402,847 to Wilson, et al. 4,414,126 also to Wilson involves the use of alkali metal mercaptobenzothiazoles as effective inhibitors for the corrosion of high lead solder in aqueous systems.
U.S. Pat. No. 4,454,050 to Bertell teaches the use of the alkali metal salts of naphthalene dicarboxylic acids to prevent sticking and staining of castings when in contact with a dye.
U.S. application Ser. No. 06/672,736 filed Nov. 19, 1984, discusses other dicarboxylic acid containing corrosion inhibiting compositions.